Related Experiment Video
Updated: Sep 23, 2026
Cell Type-specific Gene Expression Profiling in the Mouse Liver
Published on: September 17, 2019
Plasma membrane Ca2+-ATPase mRNA expression in murine hepatocarcinoma and regenerating liver cells
Blanca Delgado-Coello1, Juan Santiago-García, Angel Zarain-Herzberg
1Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, DF Mexico.
Abstract:
The plasma membrane calcium ATPase (PMCA) is an ubiquitous enzyme that extrudes calcium from the cytoplasm to the extracellular space. Four PMCA genes through alternative splicing produce a large diversity of isoforms of this enzyme. We reported previously that the PMCA contained in AS-30D hepatocarcinoma cells showed significant differences in activity in comparison to normal and regenerating liver. In the present study we investigate if the difference in PMCA activity could be related to differential expression of mRNAs encoding different isoforms of PMCA. Using RT-PCR we found that variants 1b, 1x, and 4b are expressed in all liver samples. The hepatoma AS-30 and liver at 2 days of regeneration express low amounts of isoforms 2w, 4b and 4x, and do not express isoforms 4a, 4d and 4z. Fetal and neonatal liver do not express variants 4a and 4d, but they do express variants 4x and 4z. Immunoblot analysis showed a higher ratio ATPase/total protein in the hepatoma AS-30D in comparison to normal liver. Our results suggest that the Ca2+-ATPase kinetic pattern previously observed by us in the AS-30D cells, could be at least partially explained by changes in the mRNA expression of several of the PMCA isoforms expressed in the liver.
Insights
Altered expression of plasma membrane calcium ATPase (PMCA) isoforms in liver cancer may explain differences in enzyme activity. This study identifies specific PMCA variants expressed in hepatoma and regenerating liver tissues.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- The plasma membrane calcium ATPase (PMCA) is crucial for calcium extrusion from the cytoplasm.
- Alternative splicing of four PMCA genes generates diverse enzyme isoforms.
- Previous studies noted altered PMCA activity in AS-30D hepatocarcinoma cells compared to normal liver.
Purpose of the Study:
- To investigate if differential mRNA expression of PMCA isoforms underlies the altered PMCA activity in AS-30D hepatocarcinoma cells.
- To compare PMCA isoform expression patterns in hepatoma, regenerating liver, and fetal/neonatal liver.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) to detect PMCA mRNA variants.
- Immunoblot analysis to assess the ratio of ATPase to total protein.
Main Results:
- PMCA variants 1b, 1x, and 4b were expressed in all liver samples.
- Hepatoma AS-30 and regenerating liver showed low expression of isoforms 2w, 4b, and 4x, and lacked 4a, 4d, and 4z.
- Fetal and neonatal liver lacked variants 4a and 4d but expressed 4x and 4z.
- Hepatoma AS-30D exhibited a higher ATPase/total protein ratio than normal liver.
Conclusions:
- Changes in the mRNA expression of specific PMCA isoforms likely contribute to the altered Ca2+-ATPase kinetic pattern observed in AS-30D hepatocarcinoma cells.
- Differential expression of PMCA isoforms is a key factor in liver cancer-related cellular calcium regulation.
